400个数据像这样：
152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152
155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155
155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155
237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 152 237 24 27 27 109 152 155 155 237
24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24
27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27
27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27
109 152 155 152 237 24 27 27 109 152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 109
152 155 155 237 24 27 27 109 152 155 155 237 24 27 27 98 152 152 155 237 24 27 27 109 152
155 155 237 24 27 27 98 152 155 155 237 24 27 27 109 152 152 155 226 24 27 27 98 152 152
155 226 24 27 27 98 152 152 155 226 24 24 27 98 152 152 155 226 24 24 27 98 152 152 155
226 24 24 27 98 152 152 155 226 24 24 27 98 152 152 155 226 24 27 27 98 152 152 155 226
24 27 27 98 152 155 155 226 24 27 27 98 152 155 155 226 24 27 27 98 152 155 155 226 24
27 27 98 152 155 155 226 24 27 27 98 152 152 155 226 24 24 27 98 152 152 155 226 24 24
27 98 152 152 155 226 24 24 27 98 152 152 155 226 24 24 27 98 152 152 155 226 24 24 27
98 152 152 155 226 24 24 27 98 152 152 155 226 24 27 27 98 152 152 155 226 24 27 27 98
曲线像这样:

问，怎么求该离散型数据的变化周期?
答案：迭代，方差。
算法如下：

#include <iostream>
#include <fstream>  
#include <string>
#include <istream>
#include <sstream>
using namespace std;
#define ARRAYLEN 24
#define TOTAL_SAMPLES 400
int main(){
	int samples_Data[TOTAL_SAMPLES];
	ifstream infile("test.txt");
	string data;
	int count_samples_Data=0;
	while (getline(infile, data)) {
		//cout<< data << endl;
		//string str = "92 20 120.7";
		int num1 = 0, num2 = 0, num3 = 0,num4 = 0, num5 = 0, num6 = 0,num7 = 0, num8 = 0, num9 = 0,num10 = 0, num11 = 0, num12 = 0,
			num13 = 0, num14 = 0, num15 = 0,num16 = 0, num17 = 0, num18 = 0,num19 = 0, num20 = 0, num21 = 0,num22 = 0, num23 = 0, num24 = 0,num25 = 0;
		istringstream string_to_num(data);
		string_to_num >>num1 >> num2 >> num3 >>num4 >> num5 >> num6 >>num7 >> num8 >> num9 >>num10 >> num11 >> num12 >>
			num13 >> num14 >> num15 >>num16 >> num17 >> num18 >>num19 >> num20 >> num21 >>num22 >> num23 >> num24 >>num25 ;

		samples_Data[count_samples_Data]=num1;samples_Data[count_samples_Data+1]=num2;samples_Data[count_samples_Data+2]=num3;samples_Data[count_samples_Data+3]=num4;samples_Data[count_samples_Data+4]=num5;
		samples_Data[count_samples_Data+5]=num6;samples_Data[count_samples_Data+6]=num7;samples_Data[count_samples_Data+7]=num8;samples_Data[count_samples_Data+8]=num9;samples_Data[count_samples_Data+9]=num10;
		samples_Data[count_samples_Data+10]=num11;samples_Data[count_samples_Data+11]=num12;samples_Data[count_samples_Data+12]=num13;samples_Data[count_samples_Data+13]=num14;samples_Data[count_samples_Data+14]=num15;
		samples_Data[count_samples_Data+15]=num16;samples_Data[count_samples_Data+16]=num17;samples_Data[count_samples_Data+17]=num18;samples_Data[count_samples_Data+18]=num19;samples_Data[count_samples_Data+19]=num20;
		samples_Data[count_samples_Data+20]=num21;samples_Data[count_samples_Data+21]=num22;samples_Data[count_samples_Data+22]=num23;samples_Data[count_samples_Data+23]=num24;samples_Data[count_samples_Data+24]=num25;

		count_samples_Data+=25;

		//cout << num1 <<" "<< num2 <<" "<< num3 <<" "<<num4 <<" "<< num5 <<" "<< num6 <<" "<<num7 <<" "<< num8 <<" "<< num9 <<" "<<num10 <<" "<< num11 <<" "<< num12 <<" "<<
		//num13 <<" "<< num14 <<" "<< num15 <<" "<<num16 <<" "<< num17 <<" "<< num18 <<" "<<num19 <<" "<< num20 <<" "<< num21 <<" "<<num22 <<" "<< num23 <<" "<< num24 <<" "<<num25<<endl ;

	}



	int omiga=0;
	int startIndex=0;
	int tempSum=0.0;
	int loopT=0;
	double tempAvg=0.0;
	double fangcha=0.0;
	unsigned char datas[5];
	double fangchaArray[ARRAYLEN]={0.0};
	int count=0;
	for (omiga=0;omiga<ARRAYLEN;omiga++	)
	{
		count=0;
		for (count =0 ;count<5;count++)
		{
			datas[count]=samples_Data[startIndex+count*(omiga+1)];
		}
		//计算datas 五个数据的方差
		tempSum=0.0;
		for (count =0 ;count<5;count++)
		{
			tempSum+=datas[count];
		}
		tempAvg=(double)(tempSum/5);
		tempSum=0.0;
		for (count =0 ;count<5;count++)
		{
			tempSum+=(datas[count]-tempAvg)*(datas[count]-tempAvg);
		}
		fangcha=(double)(tempSum/5);
		fangchaArray[omiga]=fangcha;
	}
	fangcha=fangchaArray[0];
	double preDaoShu=0.0;
	double postDaoShu=0.0;
	for (omiga=0;omiga<ARRAYLEN;omiga++	){
		if (fangcha>fangchaArray[omiga])
		{
			fangcha=fangchaArray[omiga];
			loopT=omiga+1;
		}
	}
	cout<<"loopT:  "<<loopT<<endl;
	
	system("pause");
	return 0;
}

/*
C++中引入了 istringstream、ostringstream、stringstream这三个类来进行不同类型数据的转换，要使用它们创建对象就必须包含 <sstream> 这个头文件。

istringstream类用于执行C++风格的串流的输入操作。
istringstream对象可以绑定一行字符串，然后以空格为分隔符把该行分隔开来。在读取数据文件时可以按行读取数据并存储到字符串中，然后通过istringstream字符串分割开，并存储到相应类型的变量中。语法格式如下：

istringstream::istringstream(string str);
1
将一个字符串中数字分割开并赋值给double类型的变量：

string str = "92 20 120.7";
double num1 = 0, num2 = 0, num3 = 0;
istringstream string_to_num(str);
string_to_num >> num1 >> num2 >> num3 ;
cout << num1 << endl << num2 << endl << num3 ;
————————————————
版权声明：本文为CSDN博主「还是要努力呀！」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/qq_33021529/article/details/115462166
*/